Dissimilar Friction Stir Butt Welding of Aluminum and Copper with Cross-Section Adjustment for Current-Carrying Components

Abstract

Abstract:Manufacturing dissimilar joints of aluminum and copper is a challenging task. However, friction stir welding (FSW) was found to be a suitable technique to produce aluminum-copper joints. Due to different electrical conductivities between aluminum and copper, an adjustment of the cross-section is required to realize electrical conductors free of resistive losses. Taking this into account, this paper presents initial results on the mechanical and electrical properties of friction stir butt welded aluminum and copper blanks having thicknesses of 4.7 mm and 3 mm, respectively. Three different approaches were investigated with the aim to produce sound welds with properties similar to those of the used base materials. Friction stir welding has been conducted at a welding speed of 450 mm/min. Subsequently, the welded specimens were subjected to metallographic analysis, tensile testing, and measurements of the electrical conductivity. The ultimate tensile force of the best joints was about 10 kN, which corresponds to joint efficiencies of approximately 72% of the aluminum base material. The analysis of electrical joint properties led to very promising results, so that the potential of FSW of Al-Cu butt joints with sheets having different thicknesses could be confirmed by the investigations carried out.

Optimization of Process Parameters for Friction Stir Welding of Aluminum and Copper Using the Taguchi Method

“…However, joining aluminum and copper is a challenging task by means of conventional fusion welding. Different melting temperatures of the base materials, the high thermal conductivities, and the low mutual solubility, which leads to the formation of brittle intermetallic phases, make it difficult to achieve sound welds [4]. Instead, joining processes in which the formation of a melt is avoided are receiving much interest [5].…”

Dissimilar Metal Welding

“…This special issue of Metals covers sixteen articles [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] focused on dissimilar metal joining techniques. Some of the published reports have confirmed the increasing interest in solid state welding processes, in particular friction based welding [6][7][8][9][10] and electromagnetic pulse welding [11,12], due to benefits related to the properties and achievable microstructure, and to energy and environmental considerations. Other papers dealt with fusion welding techniques, mainly laser based [13][14][15][16], among others [5,17], and brazing processes [18,19].…”

“…The automotive sector has witnessed the emerging trend of incorporating Cu-based materials in electrical components. The solid state joining of dissimilar Cu alloys, and of Cu alloys with Al alloys, is the focus of articles [8,9], respectively. In the former, Sun et al successfully welded dissimilar CuNiCrSi and CuCrZr in a butt joint configuration using FSW.…”

“…The transformation of coarse grains in the base metal (BM) into fine equiaxed grains in the nugget zone (NZ) was observed. In the latter, Eslami et al pointed out that an adjustment of the cross-section is required to realise electrical conductors free of resistive losses [9]. In [10], Zhou et al carried out friction stir spot welding-brazing of aluminium alloy and a hot-dip aluminized titanium alloy, using a Zn interlayer to extend the extremely narrow joining area, generally addressed as the main drawback of FSSW process.…”

Friction Stir Spot Welding of Aluminum and Copper: A Review

“…Solid-state welding processes (FSW, FSSW, USW, EMPW, etc.) have been widely applied to retard the growth of brittle IMCs on the interfaces of dissimilar metals [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. As a solid-state welding process, friction stir welding (FSW, invented by TWI, 1991 [13][14][15][16]) can avoid the aforementioned problems in Al-Cu fusion welding joints to a considerable degree due to its low welding temperature and the fierce stirring effect during dynamic welding process.…”